Field of the Invention
The present invention relates to an external preparation containing a basic medicament. Specifically, the present invention relates to a composition containing sorbic acid as a transdermal absorption accelerator.
Description of the Related Art
Several techniques for improving percutaneous absorption of a basic medicament are known. For example, the lipid solubility of a basic medicament may be adjusted by forming an equimolar salt of the basic medicament and an organic acid (Patent Document 1). An ionic liquid consisting of an aliphatic acid and an organic amine compound has also been used as a transdermal absorption accelerator (Patent Document 2). However for some medicaments, better absorbability was still required or a long-term stable formulation couldn't be obtained with conventional technique.
Sorbic acid is known as an antiseptic gent, and can be utilized for a water-based adhesive patch such as cataplasms (Patent Document 3). However, it has not been known that sorbic acid can exhibit an excellent transdermal absorbability accelerating effect for the basic medicament. Neither using them as a transdermal absorption accelerator nor a non-aqueous absorption composition has been known.